Dallara has designed structural pieces for the sides of the IZOD IndyCar Series chassis with the goal of further reducing the risk of cars potentially rotating on side impact.

The Side Impact Structures, which are mandatory for the 19-race 2013 season, are bolted to the sides of the cockpit at driver’s shoulder height and fit inside the bodywork. They are not visible outside of the car and have no aerodynamic effect.

“It is important that we continue to evolve the chassis based on the data gathered to further enhance performance and safety,” INDYCAR vice president of technology Will Phillips said. “We were extremely pleased with the performance of the new car last season and continue to study data and feedback to improve the car.”

Based on the design of the new-for-2012 car to prevent interlocking wheels, the underwing is the widest part of the car, which is unique in open-wheel racing.

“When the underwing contacts the wall, we want to achieve a progressive crush to dissipate the energy as it reaches the tub,” said Andrea Toso, head of research and development for Dallara. “The design of the underwing therefore includes some localized weak points, which fail at specific and progressive impact loads to achieve the desired dissipation. Based on information gained from some practice week incidents at the Indianapolis Motor Speedway in 2012, we decided to modify these weak points.

“For Indy, we added slots in the support cones for the underwing, and prior to Fontana we added slots in the leading edge of the underwing. These modifications have made the underwing collapse more progressively in a side impact, resulting in less load being transmitted to the driver.”

Toso noted that incorporating Side Impact Structures complements the 2012 modifications. Additionally, the sides of the chassis are reinforced with Zylon panels and thicker padding in the cockpit works in conjunction with the helmet, headrest and head restraint system to protect the occupant.

“In order to further reduce the risk of tilt, we needed to get a more even distribution of crash resistance from top to bottom. This is the purpose of the Side Impact Structure,” Toso added.